Content management system supporting third-party code

1. A computer-implemented method comprising: retrieving, by a client device, a content item from a first domain of a content management system; identifying, by the client device, a portion of the content item that references third-party code stored in a second domain of the content management system and isolated from the first domain of the content management system; requesting, by the client device, the third-party code from the second domain of the content management system; generating, by the client device, third-party content by executing the third-party code; inserting, by the client device, the third-party content into the portion of the content item; sending, by the client device to the first domain of the content management system, a request to be relayed by the first domain for additional third-party content from a source external to the content management system; receiving, from the first domain of the content management system, the additional third-party content in response to the request; rendering, by the client device, the content item with the third-party content and the additional third-party content; and maintaining a same-origin policy configured to restrict access of the third-party code to content of the content item located outside of the portion of the content item that references the third-party code based on having different domains.

2. The computer-implemented method of claim 1 , wherein when the client device lacks a copy of credentials for accessing the additional third-party content, the client device gains access to the additional third-party content using credentials stored on the content management system.

3. The computer-implemented method of claim 1 , further comprising: generating, based on execution of the third-party code, data associated with the third-party code; and transmitting the data associated with the third-party code to the content management system for storage.

4. The computer-implemented method of claim 1 , further comprising: generating, based on execution of the third-party code, data associated with the third-party code; and transmitting the data associated with the third-party code to the source external to the content management system for storage.

5. The computer-implemented method of claim 1 , wherein execution of the third-party code is sandboxed from the content item.

6. The computer-implemented method of claim 5 , wherein the third-party code is configured to retrieve data associated with the content item via a postMessage interface.

7. The computer-implemented method of claim 1 , wherein the third-party code originates from a third-party that is external to the content management system and separate from the client device.

8. The computer-implemented method of claim 1 , wherein the portion of the content item that references the third-party code is an iframe.

9. The computer-implemented method of claim 1 , wherein the portion of the content item that references the third-party code is a hidden iframe and wherein the third-party content is non-displayable content rendered in the hidden iframe.

10. The computer-implemented method of claim 1 , wherein the third-party content comprises at least one of a picture, a video, a document, an audio file, or a widget.

11. A non-transitory computer readable medium comprising instructions, the instructions, when executed by a computing system, cause the computing system to: retrieve, by a client device, a content item from a first domain of a content management system; identify, by the client device, a portion of the content item that references third-party code stored in a second domain of the content management system; request, by the client device, the third-party code from the second domain of the content management system; execute, by the client device, the third-party code in the portion of the content item, the third-party code retrieved from the second domain of the content management system that is isolated from the first domain of the content management system, wherein the third-party code is executed according to a same-origin policy, wherein access is restricted based on code with different origins; send, by the client device to the first domain of the content management system, a request to be relayed by the first domain for third-party content from a source external to the content management system; receive, from the first domain of the content management system, the third-party content in response to the request; and render, by the client device, the content item with the third-party content.

12. The non-transitory computer readable medium of claim 11 , wherein the executing of the third-party code in the portion of the content item causes the computing system to: produce additional third-party content; insert the additional third-party content into the portion of the content item; and render the content item with the additional third-party content.

13. A client device comprising: one or more processors; and at least one non-transitory computer-readable medium storing instructions that, when executed by the one or more processors, cause the one or more processors to: retrieve, by the client device, a content item from a first domain of a content management system; identify, by the client device, a secure portion of the content item that references third-party code, the third-party code stored in a second domain of the content management system and isolated from the first domain of the content management system; request, by the client device, the third-party code from the second domain of the content management system; execute, by the client device, the third-party code in the secure portion of the content item, wherein the third-party code is executed according to a same-origin policy, wherein access is restricted based on code with different origins; send, by the client device to the first domain of the content management system, a request to be relayed by the first domain for third-party content from a source external to the content management system; receive, from the first domain of the content management system, the third-party content in response to the request; and render, by the client device, the content item with the third-party content.

14. The client device of claim 13 , wherein the third-party code was provided to the content management system by the source external to the content management system.

15. The client device of claim 14 , wherein the instructions further cause the one or more processors to: retrieve, based on the executing of the third-party code, content from the source external to the content management system.

16. The client device of claim 14 , wherein the instructions further cause the one or more processors to: retrieve, based on the executing of the third-party code, data associated with the third-party code from the content management system.

17. The client device of claim 13 , wherein the executing of the third-party code causes the one or more processors to: produce additional third-party content; and render the content item with the additional third-party content.

18. The client device of claim 17 , wherein when the client device lacks a copy of credentials for accessing the additional third-party content, the client device gains access to the additional third-party content using credentials stored on the content management system.

19. The client device of claim 13 , wherein the instructions further cause the one or more processors to: generate, based on execution of the third-party code, data associated with the third-party code; and transmit the data associated with the third-party code to the content management system for storage.

20. The client device of claim 13 , wherein the instructions further cause the one or more processors to: generate, based on execution of the third-party code, data associated with the third-party code; and transmit the data associated with the third-party code to the source external to the content management system for storage.